How to handle no input using input() function in Python?

Question

I tried to write a program which requests user to choose an option, however, Python always show an error message if user choose nothing and only input ENTER. Here is an example

tmp=input("Choose program type:1.C++;2.Python;3.PERL (ENTER for default 2.Python)")
print tmp, type(tmp)   #test input
if len(str(tmp)) == 0:
  tmp=0

if tmp == 1:
  print "User choose to create a C++ program.\n"
  DFT_TYPE=".cpp"
elif tmp ==2:
  print "User choose to create a Python program.\n"
  DFT_TYPE=".py"
elif tmp ==3:
  print "User choose to create a PERL scripts.\n"
  DFT_TYPE=".pl"
else:
  print "User choose incorrectly. Default Python program would be     created.\n"  
DFT_TYPE=".py"

if I input ENTER only, I got error message like below

Traceback (most recent call last):   File "./wcpp.py", line 17, in <module>
    tmp=input()   File "<string>", line 0

    ^ SyntaxError: unexpected EOF while parsing

How to handle such case if user input nothing? Any further suggestion would be appreciated.

Works fine in Python 3 btw. Not sure if it's an earlier version issue — karthik sarpatwari
– karthik sarpatwari, Commented Jan 3, 2018 at 3:36

Abhijith Asokan · Accepted Answer · 2018-01-03 03:42:44Z

1

Since you are using python 2, use raw_input() instead of input().

tmp=raw_input("Choose program type:1.C++;2.Python;3.PERL (ENTER for default 2.Python)")
...
...
if tmp!='':
    tmp = int(tmp)
    pass #do your stuff here
else:
    pass #no user input, user pressed enter without any input.

The reason you are getting error is because in python2 input() tries to run the input statement as a Python expression.

So, when user gives no input, it fails.

edited Jan 3, 2018 at 3:42

answered Jan 3, 2018 at 3:36

Abhijith Asokan

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firesurfing · Accepted Answer · 2018-01-03 03:40:03Z

1

you can use raw_input with a default value

x = raw_input() or 'default_value'

answered Jan 3, 2018 at 3:40

firesurfing

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